Two known types of stalk-like crops in the North American market are sugar cane and sorghum. Other stalk or cane type crops are recently receiving more attention with increased interest in bio-energy such as miscanthus, energy cane and giant reed. During the harvesting of sugar cane, it is known to “top” the sugar cane plant by cutting off the top portion of the plant using a separate cutter head and allowing the top of the plant to simply fall to the ground.
Sorghum is a major cereal grain that is one of the oldest known crops and is used as a staple food in many places in Africa and Asia. Sorghum is a major feed grain crop in the U.S., Mexico, Argentina, Australia, and South Africa. It is believed that sorghum was introduced into the United States in the 1700's and some believe that Benjamin Franklin introduced the first grain sorghum crop. The seed of grain sorghum is the smallest of the major spring planted field crops, such as corn and soybeans
Sorghum is a member of the grass family that is classified into four groups, those being: grain sorghums, grass sorghums, sweet sorghums, and broomcorn. Broomcorn is grown for the brush or the branches of the seed cluster with the fibers thereof being used for the making of brooms. Sweet sorghums are grown for the production of sorghum syrup which is produced from the juices pressed from the stems that is then subsequently boiled to the proper thickness. Animal feed and silage can also be made from sweet sorghums. Grassy sorghums are grown for green feed and hay, often reaching 10 feet in height. Grain sorghums are grown especially for their rounded, starchy seeds. Some grain sorghums grow as much as 15 feet or more tall with the seed being used as seed grain and the plant utilized for silage. Nearly all grain sorghums are much shorter than the other three types of sorghum and as such the collection devices used to collect seed typical grain sorghum are not ideal for collecting seed from very tall cane crops.
The use of sorghum for the production of ethanol has brought additional emphasis to the economics of sorghum production. It is known to gather sorghum grain by utilizing a regular grain header on a combine that is utilized to cut the heads from the sorghum and then process the heads through the threshing portion of a combine. A row crop attachment can be utilized to help the pickup and intake of the crop. The row crop attachments fit in front of the grain header cutter bar and have gathering points, gathering chains, and kicker wheels like a forage harvester head. Sorghum stems often catch and choke the straw walkers of a combine causing inconvenience and lost time in the cleaning of the straw walkers. Grain sorghum stalks are smaller and normally wetter to harvest than corn stalks and are more likely to be chopped up and delivered into the grain tank. Pieces of stalk return to the cylinder in the tailings and can exacerbate this condition. To handle this situation the chaffer section may be covered with sheet metal to keep the stalks out of the return flow to the cylinder.
For the harvesting of the sorghum stalk, sugar cane harvesters can be utilized that cut the stalk into billets for transfer to a wagon for further processing. Sugar cane harvesters may include a top cutting tool for the cutting off of the seed portion of the sugar cane. The seed portion of the sugarcane plant is discarded in this harvesting system since it has low amounts of sugar content. In the harvesting operation it is advantageous to use a height of cut that is substantially close to the surface of the ground to optimize the amount of the stalk harvested yet high enough to minimize any damage to the equipment by contact with the ground. Another problem with harvesting the cane too close to the ground results in increased damage to the plant, thereby decreasing the long term productivity of the cane plantation.
What is needed in the art is a sorghum or stalk-like crop harvester which removes and separately processes both the seed and biomass material in an effective and efficient manner.